Effects of verbal encouragement on force and electromyographic activations during exercise.

International audienceBACKGROUND: The aim of the present study was to examine the effects of verbal encouragement on isometric force and associated electromyographic (EMG) parameters during a handgrip task.METHODS: Twenty-three participants (12 women and 11 men) performed maximal voluntary isometric handgrip contractions following three conditions: 1) verbal encouragement (VE) condition: participants executed isometric contractions while being verbally encouraged; 2) non-verbal encouragement (nVE) condition: the same starting and stopping signal but without encouragement; 3) non-concentration and non-motivation (nCM) condition: self-initiated contractions without concentration and motivation. Start and stop of the contraction were self-initiated. The maximal voluntary force (MVF) and the maximal rate of force development (MRFD) were measured. Integrated EMG corresponding to MVF (iEMGMVF) and to MRFD (iEMGMRFD) were collected from flexor digitorum superficialis (FDS) and extensor digitorum communis (EDC) muscles.RESULTS: MVF was higher during VE compared with nVE (+11.7%; P<0.05) and nCM (+23.2%; P<0.05) conditions. Likewise, MRFD was significantly higher during VE, compared with nVE (+21.7%; P<0.05) and nCM (+55.4%; P<0.05) conditions. iEMGMVF increased for FDS and EDC during VE, compared to nVE (+26.19%, +20.5%) and nCM conditions (+68.85%, +48.91%), respectively. iEMGMRFD increased for FDS and EDC during VE, compared to nVE (+21.2%, +46.07%) and nCM conditions (+23.79%, +42.32%). Furthermore, the reproducibility of all these indices was higher with VE condition.CONCLUSIONS: Taken together, force production (MVF and MRFD) and EMG data supported the view that muscles activity is considerably influenced by the verbal encouragements during isometric force exercise

Integration of motion and cognition within the right cerebellum during motor execution and auditory verbal encouragement: An fMRI study

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Collaboration of Cerebello-Rubral and Cerebello-Striatal Loops in a Motor Preparation Task

International audienceIn this study, we used fMRI to identify brain regions associated with concentration (sustained attention) during a motor preparation task. In comparison with a non-concentration task, increased activities were observed (P < 0.05, FWEcorrected P values) in cerebellar lobules VI and VII, motor cortex, pre-supplementary motor area (pre-SMA), thalamus, red nucleus (RN), and caudate nucleus (CN). Moreover, analysis of effective connectivity inter-areal (psychophysiological interactions) showed that during preparation, concentration-related brain activity increase was dependent on Cerebellothalamo-pre-SMA-RN and Pre-SMA-CN-thalamo-M1 loops. We postulate that, while pre-SMA common to both loops is specifically involved in the movement preparation and readiness for voluntary movement through the striatum, the cerebellar lobule VI in conjunction with RN, likely through a cerebellar-rubro-olivary-cerebellar loop, might be implicated in concentration-related optimization of upcoming motor performances

Does the instruction influence voluntary force production regardless of gender during a handgrip exercise ?

International audienceThe aim of this study was to compare the results ofmaximal voluntary contraction (MVC) andmaximal rate of force development (MRFD) in women andmen during handgrip exerciseperformed following three different instructions:Oral instruction (OI):Started with audible trippingandaccompanied by encouragement during the whole muscle contraction. Triggered instruction(TI): Same as oral instruction, but without encouragement. Self-initiated instruction (SI): Thesubject himself decided to start and to stop the contraction.Women’s MVC and MRFD withOIwere higherthan SI. No significant differencehas been found between instructions in men. Ourresults suggested that women are more sensitive to the instructioneffect compared to men. Furtherexplanations will be proposed using surface EMG and fMRI measurements

Influence of affective stimuli on leg power output and associated neuromuscular parameters during repeated high intensity cycling exercises

The aim of this study was to examine the impact of emotional eliciting pictures on neuromuscular performance during repetitive supramaximal cycling exercises (RSE). In a randomized order, twelve male participants were asked to perform five 6-s cycle sprints (interspaced by 24 s of recovery) on a cycle ergometer in front of neutral, pleasant or unpleasant pictures. During each RSE, mean power output (MPO) and electromyographic activity [root mean square (RMS) and median frequency (MF)] of the vastus lateralis and vastus medialis muscles were analyzed. Neuromuscular efficiency (NME) was calculated as the ratio of MPO to RMS. Higher RMS (232.17 ± 1.17 vs . 201.90 ± 0.47 μV) and MF (68.56 ± 1.78 vs . 64.18 ± 2.17 Hz) were obtained in pleasant compared to unpleasant conditions (p < 0.05). This emotional effect persisted from the first to the last sprint. Higher MPO was obtained in pleasant than in unpleasant conditions (690.65 ± 38.23 vs . 656.73 ± 35.95 W, p < 0.05). However, this emotional effect on MPO was observed only for the two first sprints. NME decreased from the third sprint (p < 0.05), which indicated the occurrence of peripheral fatigue after the two first sprints. These results suggested that, compared with unpleasant pictures, pleasant ones increased the neuromuscular performance during RSE. Moreover, the disappearance of the beneficial effect of pleasant emotion on mechanical output from the third sprint appears to be due to peripheral fatigue

Effects of Walking Football During Ramadan Fasting on Heart Rate Variability and Physical Fitness in Healthy Middle-Aged Males

This study aimed to investigate the effect of a walking football (WF) program during Ramadan fasting (RF) on heart rate variability (HRV) indices, body composition, and physical fitness in middle-aged males. Thirty-one healthy sedentary men were randomized to WF ( n = 18) and control ( n = 13) groups. Both groups participated in RF. The WF group were involved in a training program (small-sided games) of three sessions a week during RF. The time and frequency domains of HRV, body composition, handgrip, lumbar strength, Modified Agility Test (MAT), and 6-minute walk test (6MWT) were measured before Ramadan (BR), during Ramadan (DR), and after Ramadan (AR). We reported that RF has significantly altered some parameters of HRV DR; the mean HR decreased while the mean RR, LF, and HF increased. WF had a significant effect on HRV and mean HR DR compared with BR and AR decreased while mean RR, HF and LF increased. DR, body mass decreased in both groups, while body mass index (BMI) decreased and lean mass increased only in WF group. Lower body mass and BMI levels were reported AR only in WF group. Physical capacity improved AR, compared with BR, only in the WF group with longer distance in 6MWT, shorter time(s) in MAT, and higher lumbar strength levels. We conclude that RF increases parasympathetic system activity. WF practice during RF is safe and might improve body composition, physical fitness, autonomic cardiac function, and physical fitness in middle-aged males

Imagerie cérébrale : vers une connaissance plus approfondie du système nerveux central

International audienceBrain imaging: towards a more detailed knowledge of the central nervous system. Functional imaging allowed the knowledge of the brain to progress significantly. Recent findings about modeling of the activity and the interactivity measured by functional imaging are presented, they allow to apprehend brain functioning and brain plasticity both in normal and pathophysiological conditions. The study of specific circuits in networks should make it possible to define more realistically the dynamic functioning of the central nervous system which underlies numerous brain functions.L'imagerie fonctionnelle a permis de progresser de façon significative dans la connaissance du cerveau. Elle permet d'appréhender le fonctionnement cérébral tant dans des conditions physiologiques normales que pathologiques. Nous avons souhaité faire une mise au point sur les concepts et les approches d'analyse d'images qui permettent d'aborder l'interconnectivité cérébrale, en ayant pris soin de redéfinir au préalable et le plus rigoureusement possible les notions essentielles de la biologie du neurone qui constituent le socle des hypothèses et des modèles testés en neuroimagerie. L'étude de circuits spécifiques en réseaux va permettre de cerner de façon plus réaliste le fonctionnement dynamique du SNC qui sous-tend de nombreuses fonctions cérébrales. Deux méthodes de modélisation de l'activité et de l'interactivité cérébrales mesurées par IRMf sont présentées

The effect of a daytime 60-min nap opportunity on postural control in highly active individuals

Although napping is commonly used as a strategy to improve numerous physical and cognitive performances, the efficacy of this strategy for improving postural balance has not yet been elucidated. Thus, the aim of this study was to conduct a comprehensive examination of the effect of a 60 min nap opportunity (N60) on different components of postural control. Ten highly active individuals (age = 27 ± 3.5 y, height = 1.75 ± 0.52 m, weight = 66.02 ± 8.63 kg) performed, in a randomized order, two afternoon test sessions following no nap (NN) and N60. Postural balance was assessed using the sensory organisation test (SOT), the unilateral stance test (UST), and the limits of Stability Test performed on NeuroCom(®) Smart Balance Master. The subjective rating of sleepiness before and after the nap conditions was also assessed. Compared to NN, N60 improved the composite balance score (p 0.05). Overall, a 60 min post lunch nap opportunity may be viable for improving static balance, although further work, involving larger samples and more complex motor activities, is warranted

The effect of post-lunch napping on mood, reaction time, and antioxidant defense during repeated sprint exercice

To compare the effects of two nap opportunities (20 and 90 min) to countermeasure the transient naturally occurring increased sleepiness and decreased performances during the post-lunch dip (PLD). Fourteen highly trained judokas completed in a counterbalanced and randomized order three test sessions (control (No-nap), 20- (N20) and 90-min (N90) nap opportunities). Test sessions consisted of the running-based anaerobic sprint test (RAST), simple and multiple-choice reaction times (MCRT) and the Epworth sleepiness scale (ESS). From the RAST, the maximum (Pmax), mean (Pmean) and minimum (Pmin) powers were calculated. Blood samples were taken before and after the RAST to measure the effect of pre-exercise napping on energetic and muscle damage biomarkers and antioxidant defense. N20 increased Pmax and Pmean compared to No-nap (p < 0.001, d = 0.59; d = 0.66) and N90 (p < 0.001, d = 0.98; d = 0.72), respectively. Besides, plasma lactate and creatinine increased only when the exercise was performed after N20. Both N20 (p < 0.001, d = 1.18) and N90 (p < 0.01, d = 0.78) enhanced post-exercise superoxide dismutase activity compared to No-nap. However, only N20 enhanced post-exercise glutathione peroxidase activity (p < 0.001, d = 1.01) compared to pre-nap. Further, MCRT performance was higher after N20 compared to No-nap and N90 (p < 0.001, d = 1.15; d = 0.81, respectively). Subjective sleepiness was lower after N20 compared to No-nap (p < 0.05, d = 0.92) and N90 (p < 0.01, d = 0.89). The opportunity to nap for 20 min in the PLD enhanced RAST, MCRT performances, and antioxidant defense, and decreased sleepiness. However, the opportunity of 90 min nap was associated with decreased repeated sprint performances and increased sleepiness, probably because of the sleep inertia

Effects of playing surface on physical, physiological and perceptual responses to a repeated sprint ability test: natural grass versus artificial turf

Purpose: The effect of playing surface on physical performance during a repeated sprint ability (RSA) test, and the mechanisms for any potential playing-surface-dependent effects on RSA performance, is equivocal. The purpose of this study was to investigate the effect of natural grass (NG) and artificial turf (AT) on physical performance, ratings of perceived exertion (RPE), feeling scale (FS) and blood biomarkers related to anaerobic contribution [lactate (Lac)], muscle damage [creatine kinase (CK) and lactate dehydrogenase (LDH)], inflammation [c-reactive protein (CRP)] and immune function [neutrophils (NEU), lymphocytes (LYM) and monocytes (MON)] in response to a RSA test. Methods: Nine male professional football players from the same regional team completed two sessions of RSA testing (6 × 30 s interspersed by 35 s recovery) on NG and AT in a randomized order. During the RSA test, total (sum of distances) and peak (highest distance covered in a single repetition) distance covered were determined using a measuring tape and the decrement in sprinting performance from the first to the last repetition was calculated. Before and after the RSA test, RPE, FS, and blood [Lac], [CK], [LDH], [CRP], [NEU], [LYM] and [MON] were recorded in both NG and AT conditions. Results: Although physical performance declined during the RSA blocks on both surfaces (p=0.001), the distance covered declined more on NG (15%) compared to AT [11%; p=0.04, ES=-0.34, 95% CI (-1.21, 0.56)] with a higher total distance covered (+6 ± 2%) on AT [p=0.018, ES=1.15, 95% CI (0.16, 2.04)]. In addition, lower RPE [p=0.04, ES=-0.49, 95% CI (-1.36, 0.42)] and blood [Lac], [NEU] and [LYM] [p=0.03; ES=-0.80, 95% CI (-1.67, 0.14); ES=-0.16, 95% CI (-1.03, 0.72) and ES=-0.94, 95% CI (-1.82, 0.02), respectively)] and more positive feelings [p=0.02, ES=0.81, 95%CI (-0.13, 1.69)] were observed following the RSA test performed on AT compared to NG. No differences were observed in the remaining physical and blood markers. Conclusion: These findings suggest that RSA performance is enhanced on AT compared to NG. This effect was accompanied by lower fatigue perception and blood [Lac], [NEU] and [LYM], and a more pleasurable feeling. These observations might have implications for physical performance in intermittent team sports athletes who train and compete on different playing surfaces